Applause, applause for H-Town's philanthropic billionaires who live by the creed "to whom much is given, much is expected." Mindy and Jeff Hildebrand, No. 318 on Forbes' 2015 list of the world's billionaires, have often lived up to that expectation through their Hildebrand Foundation and most recently by pledging $10 million to the Houston Parks Board in support of its Bayou Greenways 2020 project.

The announcement was made by the Houston Parks Board on Tuesday, appropriately enough Earth Day.

When completed, the project will add 1,500 acres of new park space to the city. Connected trails will be completed along nine of Houston's major bayous. The 80 miles of new all-weather hike and bike trails will connect to existing trails for a combined total of 150 miles of bayou trails. And that, the Parks Board boasts will make Houston "one of the top 'quality of place' cities in the nation."

In a prepared statement Mindy Hildebrand, a Houston Parks Board member, said "I have a special appreciation for the quality of the planning that has gone into the Bayou Greenways project, and for the return on investment that the Houston Parks Board is achieving in bringing its plans to life. Jeff and I are deeply committed to this city that has been such a wonderful place for us to live and raise our children."

The Hildebrand Foundation pledge brings the total raised through private contributions for the $220 million project to more than $90 million. The city has committed $100 million through bond sales with the remaining $120 million to be raised with private funds.

Jeff Hildebrand formed the energy company Hilcorp in 1989 and, according to Forbes, the firm "remains on track to become the largest privately-held oil company in America."